The present invention is with respect to a tank vehicle for taking up and transporting waste material such as sludge, having a reel for a flexible aspiration or suction pipe which, when aspiration is being undertaken, is joined up with the tank of the vehicle.
In a known vehicle on these lines the reel for the aspiration pipe is placed so that its axis is horizontal and lined up generally with the length direction of the vehicle, that is to say it is fixed to the vehicle chassis or the tank thereon so that the coils of the pipe are in upright planes. However, it has now been seen from experience that the operation of such a vehicle only gives the desired effect when the aspiration pipe is completely uncoiled from the reel when aspiration is undertaken. It is thought that the reason for this is that the degree of vacuum in the coils goes up to such a high level as the waste material is moving through the pipe that there is a separation of the column of waste of the tops of the coils. Completely uncoiling the pipe and then coiling it up on the reel on each cleaning operation makes the use of such a tank vehicle troublesome and slow so that, in the prior art, such reels have not been used. In general use, in fact, such undesired effects are still taken care of by joining together a number of short pieces of pipe to get the desired length of aspiration pipe. However, to do this, two workers will generally be needed so that this system as well has a high manpower need.